<!doctype html> 
<html> 
<head> 
    <meta charset="utf-8"> 
    <title></title> 
</head>
<body>
<div id='div'></div>
<script type="text/javascript">
/*
HTMLBodyElement.prototype.wangyuechao=function(o){
	o.style.width = '200px';
	o.style.height = '300px';
	o.style.background = 'black';
	//alert('zhendaigan');
}

document.body.wangyuechao(div);
*/
//var a = document.body
//alert(null.constructor);
//alert(typeof null)

//
/*
var a = null;
b = a;
b.c = 10;
alert(a.c);
*/


</script>
</body>
</html>